Overhearing a language during childhood.

Despite its significance for understanding of language acquisition, the role of childhood language experience has been examined only in linguistic deprivation studies focusing on what cannot be learned readily beyond childhood. This study focused instead on long-term effects of what can be learned best during childhood. Our findings revealed that adults learning a language speak with a more native like accent if they overheard the language regularly during childhood than if they did not. These findings have important implications for understanding of language-learning mechanisms and heritage-language acquisition.